Many industrial manufacturing processes use presses, such as high-pressure presses. A common type of press, e.g. for machining aluminium pieces, comprises a pressure vessel in which the actual pressing operation takes place and, which is provided with some type of closure, such as a cover. Traditionally, the cover has been screwed to the wall of the pressure vessel by means of a threaded connection. After each pressing operation when a processed material is to be removed from the press, the cover has to be unscrewed, which is a time-consuming procedure.
U.S. Pat. No. 4,565,297 discloses an alternative embodiment of the closure between cover and pressure vessel, several support segments being arranged between the cover and the pressure vessel. The sealing force which originates from the cover is transmitted via these segments to the pressure vessel. In particular, the force transmission takes place via parallel, specially designed contact surfaces. The disadvantage of the shown construction is that the segments are exposed to great strain at the risk of pressure concentrations arising in certain portions, which can lead to the segments cracking and needing to be replaced earlier than desirable.
Another disadvantage is that any transverse forces acting on the segments can make the segments slide upwards to the axis of the pressure vessel and, therefore, it has been necessary to arrange special locking elements which with their vertical contact surfaces against the segments and the cover, respectively, prevent such a motion. In addition, the removal of the cover with the purpose of reaching the inside of the pressure vessel seems to be a time-consuming procedure.
U.S. Pat. No. 2,821,325 discloses yet another variant of a closure for pressure vessels. Several segments having rounded contact surfaces are arranged between the cover and the pressure vessel. However, the construction is such that it is difficult to remove the cover. An actuating lever is used to tilt the segments to a desired position before the cover can be removed. Also this known technique thus involves a time-consuming procedure.